<%@ page import="java.util.ArrayList" %>
<%@ page import="java.util.HashMap" %>
<%@ page import="java.util.Map" %><%--
  Created by IntelliJ IDEA.
  User: hasee
  Date: 2021/6/2
  Time: 12:22
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
<%
//    1.值为null值的时候，为空
    request.setAttribute("emptynull",null);
//
//    2.值为空串的时候，为空
    request.setAttribute("emptystr","");
//
//    3.值为Object类型数组，长度为零的时候
      request.setAttribute("emptyArr",new Object[]{});
//    4.list集合，元素个数为零
    request.setAttribute("emptyList",new ArrayList());
//    5.map集合，元素个数为零
    Map<String,Object> map=new HashMap<>();
    map.put("key1","value1");
    request.setAttribute("emptyMap",map);
%>
    ${empty emptynull}
    ${empty emptystr}
    ${empty emptyArr}
    ${empty emptyList}
    ${empty emptyMap}
    <hr>
    ${12==12?"国哥帅":"国哥骗人"}
</body>
</html>
